Technical Field
The present invention relates generally to minimizing signal interference in communication networks, and more particularly, to a system and method for enhancing tolerance to the bandwidth filtering effect during transmission of signals over bandwidth limited communication channels in an optical communication system.
Description of the Related Art
Reducing noise and improving signal-to-noise (S/N) ratio in communication systems is a constant challenge. Traditional methods of optimizing S/N ratio include increasing the transmitted signal power and increasing the receiver sensitivity. Also, digital signal processing dramatically improves the sensitivity of a receiving unit.
Intersymbol interference (ISI) is another problem which occurs typically due to the transmission of a signal through a bandlimited channel, i.e., a channel where the frequency response is zero above a certain frequency (the cutoff frequency). Passing a signal through such a bandwidth limited channel causes a ‘bandwidth filtering effect’ in which there is removal of frequency components above this cutoff frequency and components of the frequency below the cutoff frequency may also be attenuated by the channel.
With regards, in particular, to optical communication systems, to achieve high-speed transmission rates (e.g., terabits/second per channel), multiple optical carriers typically have to be used to address the bottleneck caused by electronic components, such as drivers and digital-to-analog converters (DAC). However, due to the high cost of optical components, using less optical carriers are desirable. Moreover, such high-baudrate electrical signals usually suffer from serious intersymbol interference due to the limited bandwidth of the electronic components of the system.
Accordingly, a need exists for a system and method to improve signal quality in optical transmission systems in a cost effective and efficient manner.